A pie chart shows the parts of one total. Select one label column and one numeric series. Each slice represents that category's share of the series total. A doughnut chart presents the same comparison with an empty center. Keep the categories few enough to read, and avoid mixing component rows with a grand total.
A combo chart answers a different question. It places two related measurements in one plot, often columns for counts and a line for a rate. When the units differ, assign the rate to the secondary axis. Otherwise a decimal rate can appear flat next to a large count.
After inserting the chart, open Select Data to inspect the series. Give each series its correct range and chart type, then tick Secondary Axis for the rate. The secondary axis belongs to that series alone. The left and right scales should describe their respective units, rather than suggesting the two measurements are directly comparable.